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(1)

Wave propagation methods for hyperbolic problems on mapped

grids

A France-Taiwan Orchid Project Progress Report 2008-2009

Keh-Ming Shyue

Department of Mathematics National Taiwan University

Taiwan

(2)

Talk objective

Review a body-fitted mapped grid approach for

numerical approximation of hyperbolic balance laws in multi-D with complex geometries

Present numerical results for problems arising from Compressible inviscid gas flow

Barotropic cavitating flow

Shallow granular avalanches

ISCM II & EPMESC XII, 29 November–3 December, 2009 – p. 2/47

(3)

Mathematical model

Consider a hyperbolic balance laws of the form

∂t q (~x, t) +

N

X

j=1

∂x j f j (q, ~x) = ψ(q)

in a general multidimensional domain

~x = (x 1 , x 2 , . . . , x N ) : spatial vector, t : time

q ∈ lR m : vector of m state quantities

f j ∈ lR m : flux vector, ψ ∈ lR m : source terms

Model is assumed to be hyperbolic, where P N j=1 α j (∂f j /∂q) is

diagonalizable with real e-values ∀α j ∈ lR

(4)

Mathematical model (Cont.)

In a body-fitted mapped grid approach, we introduce a coordinate change ~x 7→ ~ ξ via

ξ = (ξ ~ 1 , ξ 2 , . . . , ξ N ) , ξ j = ξ j (~x)

that transform a physical domain Ω to a logical one Ω ˆ , see below when N = 2 ,

−1 0 1

−1.5

−1

−0.5 0

−1 −0.5 0 0.5

−2

−1.5

−1

−0.5

x 1 x 2

ξ 1

ξ 2

Ω −→ Ω ˆ

mapping

ξ 1 = ξ 1 (x 1 , x 2 ) ξ 2 = ξ 2 (x 1 , x 2 )

logical domain physical domain

ISCM II & EPMESC XII, 29 November–3 December, 2009 – p. 4/47

(5)

Mathematical model (Cont.)

In a body-fitted mapped grid approach, we introduce a coordinate change ~x 7→ ~ ξ via

ξ = (ξ ~ 1 , ξ 2 , . . . , ξ N ) , ξ j = ξ j (~x)

that transform a physical domain Ω to a logical one Ω ˆ , and so equations into the form

∂q

∂t +

N

X

j=1

∂ ˜ f j

∂ξ j = ψ(q)

with

f ˜ j =

N

X

k=1

f k ∂ξ j

∂x k

(6)

Mathematical model (Cont.)

Basic coordinate mapping relations in N = 3 are

1 0 0 0

0 ∂ x 1 ξ 1x 2 ξ 1x 3 ξ 1 0 ∂ x 1 ξ 2x 2 ξ 2x 3 ξ 2 0 ∂ x 1 ξ 3x 2 ξ 3x 3 ξ 3

= 1 J

J 0 0 0

0 J 11 J 21 J 31 0 J 12 J 22 J 32 0 J 13 J 23 J 33

where J = |∂(x 1 , x 2 , x 3 )/∂(ξ 1 , ξ 2 , ξ 3 )| = det (∂(x 1 , x 2 , x 3 )/∂(ξ 1 , ξ 2 , ξ 3 )), J 11 =

∂(x 2 , x 3 )

∂(ξ 2 , ξ 3 )

, J 21 =

∂(x 1 , x 3 )

∂(ξ 3 , ξ 2 )

, J 31 =

∂(x 1 , x 2 )

∂(ξ 2 , ξ 3 )

, J 12 =

∂(x 2 , x 3 )

∂(ξ 3 , ξ 1 )

, J 22 =

∂(x 1 , x 3 )

∂(ξ 1 , ξ 3 )

, J 32 =

∂(x 1 , x 2 )

∂(ξ 3 , ξ 1 )

, J 13 =

∂(x 2 , x 3 )

∂(ξ 1 , ξ 2 )

, J 23 =

∂(x 1 , x 3 )

∂(ξ 2 , ξ 1 )

, J 33 =

∂(x 1 , x 2 )

∂(ξ 1 , ξ 2 )

.

ISCM II & EPMESC XII, 29 November–3 December, 2009 – p. 5/47

(7)

Compressible Euler equations

Cartesian coordinate case

∂t

 ρ ρu i

E

 +

N

X

j=1

∂x j

ρu j

ρu i u j + pδ ij Eu j + pu j

=

0

−ρ∂ x i φ

−ρ~u · ∇φ

, i = 1, . . . , N

Generalized coordinate case

∂t

 ρ ρu i

E

 +

N

X

j=1

∂ξ j

ρU j

ρu i U j + p∂ x i ξ j EU j + pU j

=

0

−ρ∂ x i φ

−ρ~u · ∇φ

ρ : density, p = p(ρ, e) : pressure , e : internal energy E = ρe + ρ P N

j=1 u 2 j /2 : total energy, φ : gravitational potential

U j = ∂ t ξ j + P N

i=1 u ix i ξ j : contravariant velocity in ξ j -direction

(8)

Finite volume approximation

Employ finite volume formulation of numerical solution

Q n ijk ≈ 1

∆ξ 1 ∆ξ 2 ∆ξ 3 Z

C ijk

q(ξ 1 , ξ 2 , ξ 3 , t n ) dV

that gives approximate value of cell average of solution q over cell C ijk at time t n (sample case in 2D shown below)

i − 1 i − 1

i

i j

j

j + 1 j + 1

C ij C ˆ ij

ξ 1 ξ 2

mapping

∆ξ 1

∆ξ 2 logical domain physical domain

←−

x 1 = x 11 , ξ 2 ) x 2 = x 21 , ξ 2 ) x 1

x 2

ISCM II & EPMESC XII, 29 November–3 December, 2009 – p. 7/47

(9)

Finite volume (Cont.)

In three dimensions N = 3 , equations to be solved take

∂q

∂t +

N

X

j=1

∂ ˜ f j

∂ξ j = ψ(q)

A simple dimensional-splitting method based on wave propagation approach of LeVeque et al. is used, i.e. ,

Solve one-dimensional Riemann problem normal at each cell interfaces

Use resulting jumps of fluxes (decomposed into each wave family) of Riemann solution to update cell

averages

Introduce limited jumps of fluxes to achieve high

resolution

(10)

Finite volume (Cont.)

Basic steps of a dimensional-splitting scheme ξ 1 -sweeps: solve

∂q

∂t + ∂ ˜ f 1

∂ξ 1 = 0 updating Q n ijk to Q ijk

ξ 2 -sweeps: solve

∂q

∂t + ∂ ˜ f 2

∂ξ 2 = 0 updating Q ijk to Q ∗∗ ijk

ξ 3 -sweeps: solve

∂q

∂t + ∂ ˜ f 3

∂ξ 3 = 0, updating Q ∗∗ ijk to Q n+1 ijk

ISCM II & EPMESC XII, 29 November–3 December, 2009 – p. 9/47

(11)

Finite volume (Cont.)

Consider ξ 1 -sweeps, for example, First order update is

Q ijk = Q n ijk − ∆t

∆ξ 1

h A + 1 ∆Q  n

i−1/2,jk + A 1 ∆Q  n

i+1/2,jk

i

with the fluctuations

(A + 1 ∆Q) n i−1/2,jk = X

m:(λ 1,m ) n i−1/2,jk >0

(Z 1,m ) n i−1/2,jk

and

(A 1 ∆Q) n i+1/2,jk = X

m:(λ 1,m ) n i+1/2,jk <0

(Z 1,m ) n i+1/2,jk

1,m ) n ι−1/2,jk & (Z 1,m ) n ι−1/2,jk are in turn wave speed and f -waves

for the mth family of the 1D Riemann problem solutions

(12)

Finite volume (Cont.)

High resolution correction is

Q ijk := Q ijk − ∆t

∆ξ 1

  ˜ F 1  n

i+1/2,jk −  ˜ F 1  n

i−1/2,jk



with ( ˜ F 1 ) n i−1/2,jk = 1 2

m w

X

m=1



sign (λ 1,m )



1 − ∆t

∆ξ 11,m |



Z ˜ 1,m

 n

i−1/2,jk

Z ˜ ι,m is a limited value of Z ι,m

It is clear that this method belongs to a class of upwind schemes, and is stable when the typical CFL (Courant-Friedrichs-Lewy) condition:

ν = ∆t max m1,m , λ 2,m , λ 3,m )

min (∆ξ 1 , ∆ξ 2 , ∆ξ 3 ) ≤ 1,

ISCM II & EPMESC XII, 29 November–3 December, 2009 – p. 11/47

(13)

Smooth vortex flow: accuracy test

Compressible Euler equations with ideal gas law Initial condition for vortex is set by

ρ =



1 − 25(γ − 1)

8γπ 2 exp (1 − r 2 )

 1/(γ−1)

, p = ρ γ ,

u 1 = 1 − 5

2π exp ((1 − r 2 )/2) (x 2 − 5) , u 2 = 1 + 5

2π exp ((1 − r 2 )/2) (x 1 − 5) , r = p(x 1 − 5) 2 + (x 2 − 5) 2

kE z k 1 ,∞ = kz comput − z exact k 1 ,∞ : discrete 1 - or

maximum-norm for state variable z

(14)

Smooth vortex flow: accuracy test

Density contours on a 40 × 40 grid at time t = 10

0 2 4 6 8 10

0 2 4 6 8 10

0 2 4 6 8 10

0 2 4 6 8

Cartesian grid 10 Quadrilateral grid

x 1

x 1

x 2

x 2

ISCM II & EPMESC XII, 29 November–3 December, 2009 – p. 13/47

(15)

Smooth vortex flow: accuracy test

Cartesian grid results

Mesh size 40 × 40 80 × 80 160 × 160 320 × 320 Order

kE ρ k 1 7.0710(−1) 1.9186(−1) 4.7927(−2) 1.1941(−2) 1.97

kE p k 1 8.5264(−1) 2.3594(−1) 5.9209(−2) 1.4721(−2) 1.96

kE u 1 k 1 2.3716(00) 6.1437(−1) 1.5298(−1) 3.8204(−2) 1.99

kE u 2 k 1 1.9377(00) 4.7673(−1) 1.1773(−1) 2.9262(−2) 2.02

kE ρ k 1.4587(−1) 3.8860(−2) 9.5936(−3) 2.3179(−3) 2.00

kE p k 1.8528(−1) 5.0122(−2) 1.2401(−2) 3.0285(−3) 1.98

kE u 1 k 3.9934(−1) 1.0488(−1) 2.4857(−2) 6.1654(−3) 2.01

kE u 2 k 2.0948(−1) 5.5860(−2) 1.3506(−2) 3.3386(−3) 2.00

(16)

Smooth vortex flow: accuracy test

Quadrilateral grid results

Mesh size 40 × 40 80 × 80 160 × 160 320 × 320 Order kE ρ k 1 1.1921(00) 4.1732(−1) 1.6058(−1) 7.0078(−2) 1.36 kE p k 1 1.4984(00) 5.3128(−1) 2.1063(−1) 9.3740(−2) 1.33 kE u 1 k 1 2.7085(00) 8.5937(−1) 2.8118(−1) 1.0743(−1) 1.56 kE u 2 k 1 2.3014(00) 7.4990(−1) 2.7248(−1) 1.1608(−1) 1.44 kE ρ k 1.8793(−1) 6.2063(−2) 1.9104(−2) 7.0730(−3) 1.59 kE p k 2.2841(−1) 7.2502(−2) 2.1285(−2) 7.9266(−3) 1.63 kE u 1 k 4.0762(−1) 1.3207(−1) 4.2383(−2) 1.5737(−2) 1.57 kE u 2 k 2.6456(−1) 9.0362(−2) 2.7416(−2) 1.2385(−2) 1.50

ISCM II & EPMESC XII, 29 November–3 December, 2009 – p. 15/47

(17)

Shock waves over circular array

A Mach 1.42 shock wave in water over a circular array

t=0

shock

(18)

Shock waves over circular array

Grid system

−3 −2 −1 0 1 2 3 4 5

−4

−3

−2

−1 0 1 2 3 4

time=0

ISCM II & EPMESC XII, 29 November–3 December, 2009 – p. 17/47

(19)

Shock waves over circular array

Contours for density

t=0.0024

(20)

Steady state shock tracking

A Mach 3 compressible gas flow over a 20 o ramp

Exact shock location (an oblique shock with 37.8 o ) is inserted into underlying grid for computation

0.0 0.2 0.4 0.6 0.8 1.0

2.02.22.42.62.83.0

Grid

M a c h

x

ISCM II & EPMESC XII, 29 November–3 December, 2009 – p. 19/47

(21)

Compressible Multiphase Flow

Homogeneous equilibrium pressure & velocity across material interfaces

Volume-fraction based model equations (Shyue JCP

’98, Allaire et al. JCP ’02)

∂t (α i ρ i ) + 1 J

N d

X

j=1

∂ξ ji ρ i U j ) = 0, i = 1, 2, . . . , m f

∂t (ρu i ) + 1 J

N d

X

j=1

∂ξ j (ρu i U j + pJ ji ) = 0, i = 1, 2, . . . , N d ,

∂E

∂t + 1 J

N d

X

j=1

∂ξ j (EU j + pU j ) = 0,

∂α i

∂t + 1 J

N d

X

j=1

U j ∂α i

∂ξ j = 0, i = 1, 2, . . . , m f − 1;

(22)

Moving cylindrical vessel

Initial setup

time=0

air helium

interface

ISCM II & EPMESC XII, 29 November–3 December, 2009 – p. 21/47

(23)

Moving cylindrical vessel

Solution at time t = 0.25

(24)

Moving cylindrical vessel

Solution at time t = 0.5

ISCM II & EPMESC XII, 29 November–3 December, 2009 – p. 23/47

(25)

Moving cylindrical vessel

Solution at time t = 0.75

(26)

Moving cylindrical vessel

Solution at time t = 1

ISCM II & EPMESC XII, 29 November–3 December, 2009 – p. 25/47

(27)

Moving cylindrical vessel

cross-sectional plot along boundary

0 1 2

0 1 2 3

ρ

0 1 2

0 1 2 3

0 1 2

0 0.5 1 1.5

0 1 2

0 0.5 1 1.5

0 1 2

0 1 2 3 4

p

0 1 2

0 1 2 3 4

0 1 2

0.5 1 1.5

0 1 2

0 0.5 1 1.5 2

t = 0.25 t = 0.5 t = 0.75 t = 1

θ(π) θ(π)

θ(π)

θ(π)

(28)

Barotropic cavitating flow

A relaxation model of Saurel et al. (JCP ’090

∂t (α 1 ρ 1 ) +

N

X

j=1

∂x j1 ρ 1 u j ) = 0,

∂t (α 2 ρ 2 ) +

N

X

j=1

∂x j2 ρ 2 u j ) = 0,

∂t (ρu i ) +

N

X

j=1

∂x j (ρu i u j + pδ ij ) = 0, i = 1, . . . , N

∂α 1

∂t +

N

X

j=1

u j ∂α 1

∂x j = 1

µ (p 11 ) − p 22 ))

Each phasic pressure p ι satisfies p ι (ρ) = (p 0 + B) (ρ/ρ 0 ) γ − B

Mixture pressure p satisfies p = α 1 p 1 + α 2 p 2 , µparameter

ISCM II & EPMESC XII, 29 November–3 December, 2009 – p. 27/47

(29)

Mixture speed of sound

Wood formula (stiffness in c ¯ vs. α )

1

ρ¯ c 2 = α ρ w c 2 w

+ 1 − α ρ g c 2 g

ρ w = 10 3 kg/m 3 , c w = 1449.4m/s, ρ g = 1.0kg/m 3 , c g = 374.2m/s

0 0.2 0.4 0.6 0.8 1

0 500 1000 1500

¯c

(30)

Cavitation test: 1D

Homogeneous gas-liquid mixture with α g = 10 −2

u 1 = −100 m/s u 1 = 100 m/s

ISCM II & EPMESC XII, 29 November–3 December, 2009 – p. 29/47

(31)

Cavitation test: 1D

Formation of cavitating gas bubble

−1 0 0 1

5

10 x 10

4

−1 0 1

−100

−50 0 50 100

u 1

−1 0 0 1

500 1000

ρ

−1 0 0 1

0.5 1

cavitation

p α

x

x

(32)

Cavitation test: 2D steady state

Uniform gas-liquid mixture with speed 600 m /s over a circular region

ISCM II & EPMESC XII, 29 November–3 December, 2009 – p. 31/47

(33)

Cavitation test: 2D steady state

Pseudo colors of volume fraction

Formation of cavitation zone (Onset–shock induced,

diffusion, . . . ?)

(34)

Cavitation test: 2D steady state

Pseudo colors of pressure

Smooth transition across liquid-gas phase boundary

ISCM II & EPMESC XII, 29 November–3 December, 2009 – p. 33/47

(35)

Cavitation test: 2D steady state

Pseudo colors of volume fraction: 2 circular case

Convergence of solution as the mesh is refined ?

t=0.05

(36)

Shallow granular avalanches

Depth-average Savage-Hutter equations

∂h

∂t +

N

X

j=1

∂x j (hu j ) = 0,

∂t (hu i ) +

N

X

j=1

∂x j



hu i u j + 1

2 β x h 2 δ ij



= hψ i , i = 1, . . . , N,

where Mohr-Coulomb closure is used with β x = K x cos ζ,

K x =

K x if ∇ · ~u > 0

K x + if ∇ · ~u < 0, K x ± = 2

cos 2 φ 1 ± r

1 − cos 2 φ cos 2 δ

!

− 1,

ψ i = sin ζδ 1i − u i

|~u| tan δ cos ζ + κu 2 1  − cos ζ ∂B

∂x i

ISCM II & EPMESC XII, 29 November–3 December, 2009 – p. 35/47

(37)

Earth pressure coefficients

Jump discontinuity on K x , |K x + − K x | 6= 0 (see below where δ = 30 o is used as a reference)

30 35 40 45 50 55 60

0 2 4 6 8 10 12 14

K x +

K x

φ (degree)

K ± x

(38)

Avalanche on an inclined channel

Hemispherical granular material

Parameters: ζ = 35 o , φ = 30 o , δ = 30 o t = 0

ISCM II & EPMESC XII, 29 November–3 December, 2009 – p. 37/47

(39)

Avalanche on an inclined channel

Contour plots for granular height (normal to channel)

0 5 10 15 20 25 30

−6

−4

−2 0 2 4 6

t = 0

(40)

Avalanche on an inclined channel

Down-flow phase

0 5 10 15 20 25 30

−6

−4

−2 0 2 4 6

t = 3

ISCM II & EPMESC XII, 29 November–3 December, 2009 – p. 38/47

(41)

Avalanche on an inclined channel

Down-flow phase

0 5 10 15 20 25 30

−6

−4

−2 0 2 4 6

t = 6

(42)

Avalanche on an inclined channel

Down-flow phase

0 5 10 15 20 25 30

−6

−4

−2 0 2 4 6

t = 9

ISCM II & EPMESC XII, 29 November–3 December, 2009 – p. 38/47

(43)

Avalanche on an inclined channel

Deposit phase

0 5 10 15 20 25 30

−6

−4

−2 0 2 4 6

t = 12

(44)

Avalanche on an inclined channel

Deposit phase

0 5 10 15 20 25 30

−6

−4

−2 0 2 4 6

t = 15

ISCM II & EPMESC XII, 29 November–3 December, 2009 – p. 38/47

(45)

Avalanche on an inclined channel

Deposit phase

0 5 10 15 20 25 30

−6

−4

−2 0 2 4 6

t = 18

(46)

Avalanche on an inclined channel

Deposit phase

0 5 10 15 20 25 30

−6

−4

−2 0 2 4 6

t = 21

ISCM II & EPMESC XII, 29 November–3 December, 2009 – p. 38/47

(47)

Avalanche on an inclined channel

Deposit phase

0 5 10 15 20 25 30

−6

−4

−2 0 2 4 6

t = 24

(48)

Avalanche on an inclined channel

Cross-sectional plot along the channel

t = 0

ISCM II & EPMESC XII, 29 November–3 December, 2009 – p. 39/47

(49)

Avalanche on an inclined channel

Down-flow phase

t = 3

(50)

Avalanche on an inclined channel

Down-flow phase

t = 6

ISCM II & EPMESC XII, 29 November–3 December, 2009 – p. 39/47

(51)

Avalanche on an inclined channel

Down-flow phase

t = 9

(52)

Avalanche on an inclined channel

Deposit phase

t = 12

ISCM II & EPMESC XII, 29 November–3 December, 2009 – p. 39/47

(53)

Avalanche on an inclined channel

Deposit phase

t = 15

(54)

Avalanche on an inclined channel

Deposit phase

t = 18

ISCM II & EPMESC XII, 29 November–3 December, 2009 – p. 39/47

(55)

Avalanche on an inclined channel

Deposit phase

t = 21

(56)

Avalanche on an inclined channel

Deposit phase

t = 24

ISCM II & EPMESC XII, 29 November–3 December, 2009 – p. 39/47

(57)

Avalanche on an inclined channel

Hemispherical granular material

Parameters: ζ = 35 o , φ = 40 o , δ = 30 o

t = 0

(58)

Avalanche on an inclined channel

Contour plots for granular height (normal to channel)

0 5 10 15 20 25 30

−6

−4

−2 0 2 4 6

t = 0

ISCM II & EPMESC XII, 29 November–3 December, 2009 – p. 41/47

(59)

Avalanche on an inclined channel

Down-flow phase

0 5 10 15 20 25 30

−6

−4

−2 0 2 4 6

t = 3

(60)

Avalanche on an inclined channel

Down-flow phase

0 5 10 15 20 25 30

−6

−4

−2 0 2 4 6

t = 6

ISCM II & EPMESC XII, 29 November–3 December, 2009 – p. 41/47

(61)

Avalanche on an inclined channel

Down-flow phase

0 5 10 15 20 25 30

−6

−4

−2 0 2 4 6

t = 9

(62)

Avalanche on an inclined channel

Deposit phase

0 5 10 15 20 25 30

−6

−4

−2 0 2 4 6

t = 12

ISCM II & EPMESC XII, 29 November–3 December, 2009 – p. 41/47

(63)

Avalanche on an inclined channel

Deposit phase

0 5 10 15 20 25 30

−6

−4

−2 0 2 4 6

t = 15

(64)

Avalanche on an inclined channel

Deposit phase

0 5 10 15 20 25 30

−6

−4

−2 0 2 4 6

t = 18

ISCM II & EPMESC XII, 29 November–3 December, 2009 – p. 41/47

(65)

Avalanche on an inclined channel

Deposit phase

0 5 10 15 20 25 30

−6

−4

−2 0 2 4 6

t = 21

(66)

Avalanche on an inclined channel

Deposit phase

0 5 10 15 20 25 30

−6

−4

−2 0 2 4 6

t = 24

ISCM II & EPMESC XII, 29 November–3 December, 2009 – p. 41/47

(67)

Avalanche on an inclined channel

Cross-sectional plot along the channel

t = 0

(68)

Avalanche on an inclined channel

Down-flow phase

t = 3

ISCM II & EPMESC XII, 29 November–3 December, 2009 – p. 42/47

(69)

Avalanche on an inclined channel

Down-flow phase

t = 6

(70)

Avalanche on an inclined channel

Down-flow phase

t = 9

ISCM II & EPMESC XII, 29 November–3 December, 2009 – p. 42/47

(71)

Avalanche on an inclined channel

Deposit phase

t = 12

(72)

Avalanche on an inclined channel

Deposit phase

t = 15

ISCM II & EPMESC XII, 29 November–3 December, 2009 – p. 42/47

(73)

Avalanche on an inclined channel

Deposit phase

t = 18

(74)

Avalanche on an inclined channel

Deposit phase

t = 21

ISCM II & EPMESC XII, 29 November–3 December, 2009 – p. 42/47

(75)

Avalanche on an inclined channel

Deposit phase

t = 24

(76)

Avalanche on an inclined channel

Pseudo colors of velocity divergence: Down-flow phase

ISCM II & EPMESC XII, 29 November–3 December, 2009 – p. 43/47

(77)

Avalanche on an inclined channel

Pseudo colors of velocity divergence: Down-flow phase

(78)

Avalanche on an inclined channel

Pseudo colors of velocity divergence: Deposit phase

ISCM II & EPMESC XII, 29 November–3 December, 2009 – p. 43/47

(79)

Avalanche on an inclined channel

Pseudo colors of velocity divergence: Deposit phase

(80)

Steady state ramp computation

A Froude 7 shallow granular flow over a 24.9 o ramp Parameters: ζ = 32.6 o , φ = 38 o , δ = 31 o

ISCM II & EPMESC XII, 29 November–3 December, 2009 – p. 44/47

(81)

Steady state ramp computation

A Froude 7 shallow granular flow over a 24.9 o ramp

Parameters: ζ = 32.6 o , φ = 38 o , δ = 31 o

(82)

Steady state ramp computation

Cross-sectional plot along ramp with three different φ

0 0.5 1 1.5 2

0

5 φ=31

φ =38 φ =50

0 0.5 1 1.5 2

0 20 40

0 0.5 1 1.5 2

−500 0 500

x

h p ∇ ·~u

ISCM II & EPMESC XII, 29 November–3 December, 2009 – p. 46/47

(83)

Future direction

Numerical methodology

Vacuum (dry) state treatment

Flux & source terms well-balanced

Interface sharping by techniques such as Lagrange-like moving mesh or front tracking

· · ·

Applications

Relaxation model as applied to more practical cavitation problems

General depth-average models to granular flows

· · ·

(84)

Future direction

Numerical methodology

Vacuum (dry) state treatment

Flux & source terms well-balanced

Interface sharping by techniques such as Lagrange-like moving mesh or front tracking

· · ·

Applications

Relaxation model as applied to more practical cavitation problems

General depth-average models to granular flows

· · ·

Thank You

ISCM II & EPMESC XII, 29 November–3 December, 2009 – p. 47/47

參考文獻

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